Carbohydrate recognition has become an important focus for the development of therapeutic strategies for the treatment of human cancers. Several prominent antitumor agents exploit selective carbohydrate DNA interactions and considerable attention is currently being directed toward the development of cancer vaccines that recognize carbohydrate antigens presented on cancer cell surfaces. These lines of investigation require quantities of pure carbohydrate structures that are difficult to obtain at present. Chemical synthesis offers a powerful solution to this dilemma. However, many desirable carbohydrate structures incorporate glycosidic linkages that continue to challenge current synthetic methodology. This research is directed toward the synthesis of key cancer-relevant oligosaccharides, including selected mucin and glycolipid antigens, as well as sugar fragments of the aureolic acids. In the course of these studies, new glycosylation methodology will be developed to solve enduring problems in oligosaccharide synthesis, including the formation of 2-deoxy-beta-glycosides, beta-mannosides, and alpha-sialosides, important constituents of many of the targeted structures. This will be accomplished through selective radical/ionic transformations of hemithio ortho esters intermediates which, in turn, are available through asymmetric synthesis or modification of readily available carbohydrates. The goal of this research is to solve persistent synthetic problems that continue to plague the chemical accessibility of oligosaccharide structures of promising value in the search for new therapeutic strategies for cancer. The present methodology will be merged with existing synthetic technology to efficiently prepare key oligosaccharides in sufficient quantity and purity for subsequent evaluation.